10 millimolar (mM) to 250 micromolar - (Aug/28/2012 )

Protip: Understand what you are doing before you rely on programs/webpages... Also merged with rest of the dilutions/calculations thread... Bob.

-calculation-

You could always use the old C1V1=C2V2: (10mM)(V1)=(0.25mM)(V2). Insert the final volume you want for V2 and solve for V1. This tells you that you need to add a certain amount of V1 to get the concentration at C2.

-Smog187-

In the above calculator, just input stock as 10, desired working concentration as 250 and volume of working solution = how much you want in the final volume, for ex if you want 50 ml put 50 ml. It would give you a value say 0.9833 so take 0.9833 of your stock i.e. your 10 mM solution and add water to it to dilute it.